Methods for advancing inverting mechanical thrombectomy apparatuses in the vasculature

ABSTRACT

Mechanical thrombectomy apparatuses (devices, systems, etc.) and methods for positioning them within a vessel and using them to remove a thrombus, e.g., clot, from within a vessel. In particular, described herein are methods of advancing an inverting tractor thrombectomy apparatus having a tractor comprising a flexible tube of material that inverts over itself as it rolls over a distal end opening of an elongate inversion support by extending the tractor region and/or a puller coupled to the tractor distally beyond the end of the catheter. Also described herein are power-driven mechanical thrombectomy apparatuses.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. provisional patentapplication No. 62/327,024, filed on Apr. 25, 2016 and titled “DOZERTHROMBECTOMY SYSTEM.”

This patent application may be related to U.S. patent application Ser.No. 15/291,015, filed on Oct. 11, 2016, titled “MECHANICAL THROMBECTOMYAPPARATUSES AND METHODS”, which is a continuation of U.S. patentapplication Ser. No. 15/043,996, filed Feb. 15, 2016, now U.S. Pat. No.9,463,035, which claims priority to each of the following provisionalpatent applications: U.S. Provisional Patent Application No. 62/284,300,filed Sep. 28, 2015; U.S. Provisional Patent Application No. 62/284,752,filed Oct. 8, 2015; and U.S. Provisional Patent Application No.62/245,560, filed Oct. 23, 2015.

Each of these patents and patent applications is herein incorporated byreference in its entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

The apparatuses and methods described herein relate to mechanicalthrombectomy apparatuses and methods.

BACKGROUND

It is often desirable to remove tissue from the body in a minimallyinvasive manner as possible, so as not to damage other tissues. Forexample, removal of tissue from within a vasculature, such as bloodclots, may improve patient conditions and quality of life.

Many vascular system problems stem from insufficient blood flow throughblood vessels. One causes of insufficient or irregular blood flow is ablockage within a blood vessel referred to as a blood clot, or thrombus.Thrombi can occur for many reasons, including after a trauma such assurgery, or due to other causes. For example, a large percentage of themore than 1.2 million heart attacks in the United States are caused byblood clots (thrombi) which form within a coronary artery.

When a thrombus forms, it may effectively stop the flow of blood throughthe zone of formation. If the thrombus extends across the interiordiameter of an artery, it may cut off the flow of blood through theartery. If one of the coronary arteries is 100% thrombosed, the flow ofblood is stopped in that artery, resulting in a shortage of oxygencarrying red blood cells, e.g., to supply the muscle (myocardium) of theheart wall. Such a thrombosis is unnecessary to prevent loss of bloodbut can be undesirably triggered within an artery by damage to thearterial wall from atherosclerotic disease. Thus, the underlying diseaseof atherosclerosis may not cause acute oxygen deficiency (ischemia) butcan trigger acute ischemia via induced thrombosis. Similarly, thrombosisof one of the carotid arteries can lead to stroke because ofinsufficient oxygen supply to vital nerve centers in the cranium. Oxygendeficiency reduces or prohibits muscular activity, can cause chest pain(angina pectoris), and can lead to death of myocardium which permanentlydisables the heart to some extent. If the myocardial cell death isextensive, the heart will be unable to pump sufficient blood to supplythe body's life sustaining needs. The extent of ischemia is affected bymany factors, including the existence of collateral blood vessels andflow which can provide the necessary oxygen.

Clinical data indicates that clot removal may be beneficial or evennecessary to improve outcomes. For example, in the peripheralvasculature, inventions and procedures can reduce the need for anamputation by 80 percent. The ultimate goal of any modality to treatthese conditions of the arterial or venous system is to remove theblockage or restore patency, quickly, safely, and cost effectively. Thismay be achieved by thrombus dissolution, fragmentation, thrombusaspiration or a combination of these methods.

Mechanical thrombectomy devices may be particularly advantageous.Depending on the size, location and extent of a clot, it may also beparticularly advantageous to mechanical retrieve and break apart theclot in a manner that is both safe and effective. There is a definiteneed for a thrombectomy device, and particularly a mechanicalthrombectomy device that can be more effective in removing tissue suchas clots from within a body. Described herein are apparatuses (devices,systems and kit) and methods of using them that may address the needsand problems discussed above.

SUMMARY OF THE DISCLOSURE

Described herein are mechanical thrombectomy apparatuses (devices,systems, etc.) and methods for using them to remove a thrombus, e.g.,clot, from within a vessel. These mechanical thrombectomy apparatusesmay be inverting tractor thrombectomy apparatuses. Typically, themechanical thrombectomy apparatuses described herein are invertingtractor thrombectomy apparatuses that includes a tractor (e.g., tractorregion, tractor portion, etc.) comprising a flexible tube of materialthat inverts over itself as it rolls over a distal end opening of anelongate inversion support. The elongate inversion support typicallycomprises a catheter having a distal end opening into which the tractorinverts. The flexible tractor inverts and rolls back into itself and maybe drawn into the elongate inversion support in a conveyor-like motion;the outward-facing region rolls around to become an inward-facingregion, e.g., within the lumen of the elongate inversion support. Therolling motion may thus draw a clot or other object within a vessel intothe elongate inversion support.

Before these apparatuses can remove a clot from a vessel, however, theymust be positioned within the vessel adjacent to the clot to be removed.As described herein, the inverting tractor thrombectomy apparatusesdescribed herein may be accurately positioned either with our withoutthe use of a guidewire or guide sleeve within a vessel by takingadvantage of the rolling motion of tractor at the distal end of theapparatus. The arrangement of the tractor, elongate inversion support(e.g. which may be or may include a catheter) and the puller connectedto the tractor may be used to easily and accurately position theapparatus adjacent a clot and remove the clot in a manner that may beboth easier and more efficient than other methods.

Described herein are methods of advancing an inverting tractorthrombectomy apparatus forward in the vasculature. These systems andmethods may use use the rolling motion of the tractor to move throughthe vasculature including over/around clot.

For example, described herein are methods of removing a clot from avessel using a mechanical thrombectomy apparatus. The mechanicalthrombectomy apparatus may include an elongate inversion support(comprising or consisting of a catheter) that extends in a long axisfrom a proximal end to a distal end, a puller extending distally withinthe elongate inversion support (e.g. catheter) and a flexible andtubular tractor, wherein the tractor is coupled to a distal end regionof the puller and further wherein the tractor is inverted over a distalend opening of the catheter so that the tractor extends proximally overthe catheter. Any of these methods may include: advancing the pullerdistally within the elongate inversion support (e.g., catheter) andwithin the vessel towards a clot, so that the tractor extends from thepuller distally beyond the distal end opening of the catheter, forming agap between the tractor and the distal end opening of the catheter;advancing the catheter distally over the puller and into the gap; anddrawing the clot into the catheter with the tractor by pulling thetractor proximally within the catheter so that the tractor rolls andinverts over the distal end opening of the catheter.

Any of these methods may include repeating the advancing steps one ormore times. For example the method may include: advancing the pullerdistally within the elongate inversion support (e.g., catheter) andwithin the vessel towards a clot, so that the tractor extends from thepuller distally beyond the distal end opening of the catheter, forming agap between the tractor and the distal end opening of the catheter;advancing the catheter distally over the puller and into the gap;repeating the advance steps until the distal end opening of the catheteris adjacent to the clot; and drawing the clot into the catheter with thetractor by pulling the tractor proximally within the catheter so thatthe tractor rolls and inverts over the distal end opening of thecatheter.

These methods for advancing the apparatus may therefore be described as“inchworm” type advancement, as the tractor is extended from within thecatheter to distally extend in the vessel, then the catheter may followthe tractor distally. In any of these methods, the tractor may be‘reset’ back into the catheter (as it may otherwise be left deployed outof the catheter along vessel), by pulling it back into the catheter. Forexample, the tractor may be pulled back into the catheter by pullingproximally on the puller once the catheter distal end opening ispositioned against the distal-facing tractor (the region doubling-backor inverting over itself) so that the tractor can roll over the distalend opening. Resetting or repositioning the tractor in this manner mayrequire that the apparatus be configured to prevent jamming (e.g.,“anti-jamming”), including one or more of: having a lubricious and/orsmooth tip, having a tip region that is more rigid than the moreproximal regions of the tip, and/or having a tractor that is biased tohave a first relaxed configuration that has an outer diameter that isgreater than the inner diameter of the catheter and a second relaxedconfiguration that has an inner diameter that is greater than the outerdiameter of the catheter, where the tractor converts between the firstand second configurations by inverting over itself (e.g., over thedistal end opening of a catheter). These configurations may prevent thetractor for buckling when pushed out of the distal end opening or whenpulled back into the distal end opening of the catheter.

In any of the variations described herein, the repeated steps of inchingforward by extending the tractor distally (e.g., pushing the pullercoupled to the tractor distally, including distally out of the distalopening of the catheter), then advancing the catheter into the gapformed by the folded-over tractor, e.g., the gap between the distal endopening of the catheter and the tractor, may also include resetting thetractor by pulling the tractor back into the catheter once the distalend of the catheter has been advanced.

In any of these methods, the steps of advancing the tractor distallyfrom the distal-end of the catheter and advancing the catheter behindthe tractor (and optionally pulling the tractor back into the catheterby pulling proximally while holding the catheter fixed (or advancing itdistally) may be repeated until the apparatus is adjacent to the clot;thereafter the clot can be removed as discussed above, by pulling thepuller proximally to draw the tractor into the catheter.

In general, drawing the clot into the catheter may include advancing thecatheter distally while pulling the pusher proximally.

In any of the methods described herein, the apparatus may be advanceddistally (or retracted proximally) without the use of a guidewire orguide catheter. For example, advancing the puller distally may compriseadvancing the puller without using a guidewire extending distal to thepuller.

As mentioned, advancing the puller may comprise extending the distal endof the puller out of the distal end opening of the catheter.Alternatively the puller may remain in the catheter when advanceddistally.

The tractor may be any appropriate tractor, including a woven, braided,or knitted tractor, or a tractor formed of a solid sheet of material(e.g., that may be cut or perforated). For example, advancing the pullermay comprise extending the tractor distally within the vessel, furtherwherein the tractor comprises a woven flexible and tubular tractor.Advancing the puller may comprise extending the tractor distally withinthe vessel, further wherein the tractor comprises a knitted tractor.

Any of the methods described herein may include using a puller andtractor having a lumen (e.g., central lumen) through which a guidewiremay be advanced. For example, advancing the puller may compriseextending the tractor distally within the vessel, further wherein thepuller comprises a central lumen configured to pass a guidewiretherethrough.

Further, any of the methods described herein may be performed in anyvessel within the body, including peripheral and neurovascular vessels.For example, any of these methods may be performed within an internalcarotid artery (e.g., advancing the puller may comprise advancing thepuller within an internal carotid artery).

Also described herein are methods of positioning a mechanicalthrombectomy apparatus within a vessel and/or removing a clot from avessel using the mechanical thrombectomy apparatus in which themechanical thrombectomy apparatus includes a puller within a firstcatheter that is within a second catheter, wherein the puller and secondcatheter are connected by a flexible and tubular tractor. For example,the method may comprise: advancing the puller distally through the firstcatheter and the second catheter and within the vessel towards a clot,so that the flexible and tubular tractor extends from the puller beyonda distal end opening of the first catheter and beyond a distal endopening of the second catheter; advancing the outer catheter distallythrough the vessel by one or more of: holding the position of the firstcatheter within the vessel and pulling the puller proximally within thefirst catheter; or moving the first catheter distally relative to thepuller; and drawing the clot into the first catheter with the flexibleand tubular tractor by pulling the flexible and tubular tractorproximally within the first catheter so that the flexible and tubulartractor rolls and inverts over the distal end opening of the catheter.Any of these methods may also include repeating the advancing stepsuntil the clot is adjacent to the distal end of the puller.

Drawing the clot into the catheter may further include advancing thefirst catheter distally while pulling the pusher proximally. Advancingthe puller distally may include advancing the puller without using aguidewire extending distal to the puller. Advancing the puller mayinclude extending the flexible and tubular tractor distally within thevessel further wherein the flexible and tubular tractor comprises awoven flexible and tubular tractor. Alternatively, advancing the pullermay include extending the flexible and tubular tractor distally withinthe vessel further wherein the flexible and tubular tractor comprises aknitted flexible and tubular tractor.

As mentioned, advancing the puller may comprise extending the flexibleand tubular tractor distally within the vessel further wherein thepuller has a central lumen configured to pass a guidewire therethrough.

In any of these methods, drawing the clot into the first catheter maycomprise uncoupling the flexible and tubular tractor from the secondcatheter.

Also described herein are mechanical thrombectomy apparatus for removinga clot from a vessel that include a motorized or motor-driven tractor.For example described herein are apparatuses including: a flexiblecatheter having a distal end and a distal end opening; a tractorcomprising a flexible belt that extends within the catheter, invertsover the distal end opening of the catheter and extends along the outerdiameter of the catheter; a power drive at a proximal end of theflexible catheter configured to drive the tractor around the catheter sothat it inverts over the distal end opening of the catheter; and aguidewire lumen through the catheter and the tractor configured to passa guidewire.

The flexible belt may comprise a flexible tube. In some variations, thetractor comprises a plurality of flexible belts that each extend withinthe catheter, invert over the distal end opening of the catheter andextend along the outer diameter of the catheter.

The the power drive may be configured to engage with the flexible belton an outer surface of the catheter. The power drive may comprise anannular ring surrounding the catheter and the tractor.

Any of these apparatuses may include an outer catheter configured toenclose the flexible catheter and tractor, wherein the flexible catheterand tractor may be inserted through the body within the outer catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1A-1H illustrate an example of a mechanical thrombectomy apparatusfor mechanically removing an object such as a clot form a body region.FIG. 1A shows an example of an elongate inversion support portion of anapparatus, configured as a catheter. For example, at least the distalend of the elongate inversion support may be configured as a catheter.FIG. 1B shows an enlarged view of a distal end (opening) of the catheterof the elongate inversion support of FIG. 1A, showing the apertureformed by the distal end opening; FIG. 1C shows an example of a distaltractor region of a flexible tube (tractor tube) extending from a puller(the puller in this example is configured as a catheter. The tractor isshown in a first (e.g., un-inverted) configuration) and may be biasedopen, e.g., by heat setting, to have an outer diameter that is greaterthan the inner diameter of the catheter of the elongate inversionsupport, as shown in FIG. 1D. FIG. 1D shows the same distal tractorregion of FIG. 1C with the expandable first end region expanded. Thisfirst configuration may be compressed down into the elongate inversionsupport and the distal end inverted over the catheter portion of theelongate inversion support, as shown in FIG. 1E. In FIG. 1E, theassembled mechanical thrombectomy apparatus with the elongate inversionsupport and the flexible tube forming the tractor is shown. The tractorextends through the catheter of the elongate inversion support anddoubles back over the distal end opening of the catheter and extendsover the outer diameter of the catheter. The outer portion of thetractor (extending along the outer diameter of the catheter) may be heldin a collapsed configuration (as shown in FIG. 1E), or it may beexpanded, as shown in FIG. 1F. Thus, the tractor may be biased so thatin the second configuration (inverted over the distal end of thecatheter), the tractor has a ‘relaxed’ outer diameter that is greaterthan the outer diameter of the catheter of the elongate inversionsupport. FIGS. 1G and 1H illustrate the use of the apparatus of FIGS. 1Eand 1F to remove a clot by drawing the flexible tube proximally and/oradvancing the catheter distally towards the clot so that the expandablefirst end region inverts as it is drawn into the distal end of thecatheter, pulling the clot into the catheter.

FIG. 1I illustrates an alternative variation of a tractor and puller. InFIG. 1I, the tractor is shown attached to the distal end of a tapered ornarrow puller; the distal end region is tapered, and includes aradiopaque marker at or near the attachment site to the tractor; thetractor may be knitted, braided, woven, etc. Thus, in some variationsthe distal end region of the puller may have a greater flexibility thanthe proximal end of the puller. The puller may be hollow (e.g., acatheter or hypotube) or solid (e.g., like a wire).

FIGS. 2A-2E illustrate a method of positioning a mechanical thrombectomyapparatus within a vessel and/or removing a clot from a vessel using themechanical thrombectomy apparatus. In FIGS. 2A-2E the apparatus is showninching distally within the vessel towards the clot using the tractor,so that the clot may be captured and removed by the tractor. In FIGS.2A-2E the apparatus is advanced distally without the use of a guidewire.

FIGS. 3A-3D illustrate a method of positioning a mechanical thrombectomyapparatus within a vessel and/or removing a clot from a vessel using themechanical thrombectomy apparatus similar to that shown in FIGS. 2A-2Eonly using a guidewire.

FIGS. 4A-4D illustrate a method of positioning a mechanical thrombectomyapparatus within a vessel and/or removing a clot from a vessel using themechanical thrombectomy apparatus in which the distal end of the puller,to which one end of the tractor is attached, is extended distally fromthe catheter.

FIGS. 5A-5C illustrate a method of positioning a mechanical thrombectomyapparatus within a vessel and/or removing a clot from a vessel using themechanical thrombectomy apparatus similar to that shown in FIGS. 4A-4Dbut include the use of a guidewire.

FIGS. 6A-6B illustrates another method of positioning a mechanicalthrombectomy apparatus within a vessel and/or removing a clot from avessel using the mechanical thrombectomy apparatus, in which theapparatus include a tractor that is connected (attached) to both thepusher and an outer catheter or element.

FIG. 7 illustrates one region (e.g., the internal carotid artery) inwhich the apparatuses and methods described herein may be used.

FIG. 8A-8B illustrate an example of a mechanical thrombectomy apparatusfor removing a clot from a vessel that include a motorized ormotor-driven tractor. FIG. 8A shows the apparatus in a side view,schematically illustrating the internal components. FIG. 8B is anexample of a catheter and tractor(s) that may be used with an apparatussuch as the one shown in FIG. 8A.

FIGS. 9A-9B illustrate a method of operating a mechanical thrombectomyapparatus for removing a clot from a vessel that include a motorized ormotor-driven tractor, such as the one shown in FIGS. 8A-8B. FIG. 9Cillustrates a motorized or motor-driven (e.g., “power driven) continuoustractor that is loaded into a larger catheter (e.g., an intermediatecatheter).

DETAILED DESCRIPTION

Described herein are mechanical thrombectomy apparatuses, includingmanually drive and power-driven apparatuses, and methods of using them.In particular, described herein are methods of positioning theseapparatuses within a vessel and/or removing clot with them that mayinclude extending the tractor region and/or the puller distally of thedistal end of the apparatus to assist in advancing the apparatusdistally.

Any of the mechanical thrombectomy apparatuses described herein may havean inverting tractor that is configured to prevent jamming and grab ablood clot. These apparatuses may include an elongate elongate inversionsupport support that supports an annulus over which the tractor invertsat the distal end. The tractor may comprise a flexible tube that doublesback over (e.g., inverts) over the distal end of the elongate invertingsupport (e.g., a catheter) so that it extends into the annuls opening ofthe elongate inverting support and an inner puller coupled to the innerend of the tractor that the tractor can be pulled proximally to pull andinvert the tractor over the annulus at the distal end of the elongateinverting support to roll and capture a clot. The apparatus may includea guidewire lumen extending through the elongate inverting support,and/or tractor puller that is configured to pass a guidewire.

The apparatuses described herein may be adapted to prevent jamming,e.g., by including a coating (e.g., hydrophilic, lubricious coating,etc.) or the like to enhance the sliding and inverting of the tractorover the distal end. Further, any of these apparatuses may include oneor more projections that are configured to enhance grabbing and/ormaceration of a clot. Grabbing of a clot may be particularly, but notexclusively, helpful when the tractor is lubricious. Although lubricioustractors may may resist jamming and require less force to operate, e.g.,inverting over the distal end of the catheter, it may be more difficultto initially grab or grasp clot when the tractor is more lubricious. Itmay also be particularly helpful to include projections that areretracted along the length of the tractor adjacent to the outer diameterof the elongate inverting support (e.g., catheter), for example, whenpositioning the apparatus within a vessel, but extend the projectionsoutward from the tractor when rolling and inverting to grab a clot.

In general, a mechanical thrombectomy apparatus for removing a clot froma vessel may be a system, assembly or device including an elongateinversion support having a distal end and a distal annulus, and aflexible tractor assembly at least partially inverted and configured toroll and invert over the distal annulus of the elongate invertingsupport.

In many of the examples described herein, the elongate inversion supportis a catheter (or a portion of a catheter at the distal end) and theannulus is formed by the distal end opening of the catheter; the tractorextends within the catheter and doubles back over the distal end of thecatheter to extend over the outer diameter of the catheter at the distalend of the catheter, although it may extend proximal for any appropriatedistance (including between 1-30 cm, between 2-20 cm, greater than 1 cm,2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm,15 cm, 20 cm, etc.). The end of the tractor within the catheter may becoupled to a puller (e.g., at a proximate puller region connected to thedistal or inner end of the tractor). The tubular tractor may include anelongate lumen that is configured to allow passage of a guidewire. Thetubular tractor may also be configured to slide along the long axiswithin the catheter lumen and invert over the distal end opening of thecatheter when the proximal end region is pulled proximally. The tractormay be referred to herein as a tractor assembly, tractor portion,tractor tube, or simply a tractor, and is typically positioned andlongitudinally slideable within the catheter, and arranged so a portionof the tractor (sometimes referred to as the “distal tractor region” or“distal-facing” tractor region) doubles back over itself

For example, FIG. 1A shows one variation of a catheter of an elongateinversion support that may form part of the apparatuses describedherein. In this example, the elongate inversion support includes acatheter 100 having a distal end region 103 that includes a distal endopening 105. The distal end region may have an increasing softness(measured by durometer, e.g., shore durometer) except that the verydistal-most end region (distal end 105, including the distal endopening) may be substantially less soft than the region immediatelyproximate to it. Thus, although the distal tip region of the catheter(e.g., the distal most x linear dimensions, where x is 10 cm, 7 cm, 5cm, 4 cm, 3 cm, 2 cm, 1 cm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm)has an increasing softness/decreasing harness extending from theproximal to distal ends, the very distal end region 107 (e.g., measuredas distal most z linear dimensions, where z is 1 cm, 9 mm, 8 mm, 7mm, 6mm, 5 mm, 4 mm, 3 mm, 2 mm, 1mm, 0.8 mm, 0.5mm, 0.3 mm, 0.2mm, etc., andz is always at least three times less than x) has a hardness that isgreater than the hardness of the region immediately proximal to it, andmay be as hard or harder than the proximal-most region of the distal tipregion.

In FIG. 1A, the elongate inversion support is an elongate hollowcatheter having a column strength that is sufficient to prevent bucklingwhen the catheter is pulled over the distal annulus (distal endopening). Thus, the elongate inversion support may be configured so thatit does not collapse (e.g., buckle) when 500 g or less of of compressiveforce is applied (e.g., at least about 700 g, 600 g, 500 g, 400 g, 300g, etc. of compressive force) for neurovascular applications. Forperipheral vascular applications the elongate inversion support may beselected or configured to withstand at least 1500 g of compressive force(e.g., at least about 2000 g, 1900 g, 1800 g, 1700 g, 1600 g, 1500 g,1400 g, etc. of compressive force). In general, any of the apparatusesdescribed herein may include a elongate inversion support that is not afull-length catheter, but may include a portion of a catheter, typicallyat the distal end, connected to a rod, wire, hypotube, or the like (aswill be described in greater detail below in reference to FIGS. 42A-43D)or may be skived. Thus, any of the apparatuses and methods describedherein may be adapted for use with an elongate inversion support that isnot limited to catheters, including elongate inversion supports thatinclude a portion of a catheter, or that include a ring or otherstructure forming the annulus at the distal end. In FIG. 1A the catheter100 of the elongate inversion support may be any appropriate type ofcatheter or portion of a catheter, including microcatheters appropriatefor neurovascular use.

In some variations the distal end 105 of the elongate inversion supportis adapted so that the tractor may slide or roll and invert over thedistal end of the catheter without being caught (binding, jamming) orwithout substantial friction. For example, in some variations the distaltip (end) may be curved or radiused 109 as shown in FIG. 1B,particularly on the outer surface (e.g., the transition from outerdiameter to inner diameter).

FIG. 1C shows an example of a flexible tractor 144 coupled to a puller146. In this example to form a pullable tractor assembly 140, thetractor is shown integrated with the puller, forming the assembly. InFIG. 1C, the tractor is a tube of material (e.g., wove, knitted,braided, etc.) that is flexible and elongate. The tractor is shownextended from the puller in a first configuration. It may beparticularly beneficial if the relaxed outer diameter of the flexibletractor in this first configuration has a greater outer diameter thanthe outer diameter of the catheter of the elongate inversion supportinto which the tractor will be positioned prior to inverting. Theflexible and tubular tractor 144 may be sufficiently soft and flexible(e.g., having a low collapse strength) so as to easily roll and foldover the distal aperture of the elongate inversion support. The puller146 may typically be a less-expandable (or non-expandable) structure(tube, puller, etc.). In the example shown in FIG. 1C, the tractor 144is configured, e.g., by shape-setting (heat setting, etc.), to expand inthe relaxed first configuration to a radial diameter that is between 1.1and 10 times the diameter of the inner diameter of the catheter of theelongate inversion support when unconstrained, as shown in FIG. 1D. InFIG. 1D, the tractor of FIG. 1C is shown in an expanded, relaxed,configuration. Thus the expandable tractor may be biased to expand open.The tractor may be formed of a mesh, braided, woven, knitted, or sheetof material and is generally adapted to grasp the object to be removed(e.g., blood clot).

In FIGS. 1C and 1D the tractor and puller have two portions, a tractor144 and a less expandable (or non-expandable) proximal portioncomprising the puller 146. The puller may be a separate region, such asa wire, catheter or hypotube, which is connected to an end region of thetractor (e.g., a flexible mesh, woven, braided, etc.), e.g., the distalend or near the distal end. The inverting region of the tractor, whereit rolls and inverts over the distal end opening of the catheter may bereferred to as the distal-facing region of the tractor, which mayactively grab clot when rolling.

In FIG. 1E, the flexible tractor of FIG. 1C is shown with the tractordoubled back over itself an over the the distal end of the catheter ofthe elongate inversion support 101. The distal end region is collapseddown, e.g., onto the puller and the elongate inversion support, and maybe held collapsed. In this example a tractor hold 188 may be used tohold the tractor collapsed down onto the outer diameter of the elongateinversion support. However, in an unconstrained or deployedconfiguration, as shown in FIG. 1F, the tractor in this secondconfiguration (e.g., the portion that is inverted over the distal end ofthe catheter) has an outer diameter that is greater than the outerdiameter of the catheter of the elongate inversion support. Thus, thetractor 144 may be biased so that it has a relaxed expandedconfiguration in the first configuration (as shown in FIG. 1C) that isgreater than the inner diameter (ID) of the catheter of the elongateinversion support portion of the apparatus and the relaxed expandedconfiguration of the second configuration (shown in FIG. 1F) invertedover the catheter has an OD that is greater than the OD of the catheter.The tractor is expandable and may be coupled to the puller. In somevariations the flexible tractor and the puller may comprise the samematerial but the tractor may be more flexible and/or expandable, or maybe connected to a push/pull wire or catheter.

FIGS. 1G and 1H illustrate the removal of a clot using an apparatus suchas the apparatus assembled from the components of FIGS. 1A and 1E. Inthis example the apparatus is configured as a thrombectomy apparatusincluding a catheter of an elongate inversion support 101 and a flexibletractor that extends over the distal end region of the catheter anddoubles-over itself at the distal end of the catheter to invert so thatthe external tractor end region is continuous with an innerless-expandable (in this example, less-expandable includesnon-expandable) second distal end region 146 (puller) that extendsproximally within the catheter and forms an inner lumen that may pass aguidewire. The pusher/puller member that may be a rod or other memberthat is continuous with the distal end region of the tractor. In FIG. 1Gthe apparatus is shown positioned and deployed within the vessel 160near a clot 155. The clot may be drawn into the catheter by pulling thetractor 140 proximally into the catheter 101, as indicated by the arrow180 showing pulling of the inner portion of the flexible tractor (e.g.,using a handle, not shown) resulting in rolling the tractor over the endopening of the catheter and into the catheter distal end and invertingthe expandable distal end region so that it is pulled into the catheter,shown by arrows 182. The end of the tractor outside of the catheter maybe “loose” relative to the outer wall of the catheter. FIG. 1Iillustrates another example of a tractor assembly 154 including atractor 144 that is coupled to a puller 156. The puller in this exampleis tapered (having tapering region 161) and may therefore have adifferent flexibility of the distal end region than the proximal endregion. For example the proximal end region may be less flexible thanthe narrower-diameter distal end region 195 to which the tractor iscoupled. The assembly includes a radiopaque marker 165. The tractor maybe attached to the puller by any appropriate means. For example, thetractor may be crimped, glued, fused, or otherwise attached to thepuller, typically permanently.

In general the mechanical thrombectomy apparatuses described herein maybe highly flexible, both before actuating and during operation. Forexample, the flexible tractor may not increase the stiffness/flexibilityof the catheter of the elongate inversion support, and particularly thedistal end region of the catheter too much, to avoid impactingmaneuverability, particularly within tortious vessels of theneurovasculature. Described herein are flexible tractor tube portionsthat increase the stiffness of the last y cm (e.g., distal most 20 cm,18 cm, 15 cm, 12 cm, 10 cm, 9 cm, 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3 cm, 2cm, 1 cm, etc.) of the catheter less than a predetermined percentage(e.g., less than 10%, 12%, 15%, 18%, 20%, 25%, 30%, etc.). For example,described herein are flexible tractor tube portions that pass throughthe catheter and double back over the distal end of the catheter butincrease the stiffness of a distal 5 cm of the catheter by less than 15%of the stiffness of the distal 5 cm of the catheter without the flexibletube extending therethrough and doubling back over the distal end of thecatheter.

Methods of Advancing an Inverting Tractor Apparatus

A mechanical thrombectomy apparatus may be advanced distally within avessel and may grab and engulf a clot that is located distally by usingthe tractor to extend distally ahead of the apparatus, and in some casespull (e.g., against the vessel walls) to guide or draw the catheterdistally forward. This method of advancement may be referred to as“inchworm” or ‘worm-like” motion within the vessel. For example, FIGS.2A-2E illustrate a first method of advancing a mechanical thrombectomyapparatus and/or removing a clot from a vessel using the mechanicalthrombectomy apparatus. In this example, the apparatus includes acatheter 205 extending proximally to distally, a puller 207 (shown as athin tube or hypotube, though it may be a wire or rod, as mentionedabove), extending distally within the catheter and a flexible andtubular tractor 209. The tractor is coupled to a distal end region ofthe puller 217 and the tractor is inverted over a distal end opening ofthe catheter 219 so that the tractor extends proximally over the outside(outer diameter) of the catheter. In operation, the apparatus may beadvanced distally (e.g., towards a clot 213) in a vessel 211, as shownin FIGS. 2B-2D. In FIG. 2B, the puller is pushed distally 220 (shown byarrows on the left) to advanced distally within the catheter and withinthe vessel towards a clot, so that the tractor extends from the pullerdistally beyond the distal end opening of the catheter 218, forming agap 219 between the tractor and the distal end opening of the catheter.This gap is an annular, distal-facing cavity (e.g. pouch) formed in thetractor, and into which the distal end opening of the catheter may beadvanced, as shown in FIG. 2C. In FIG. 2C, the catheter is advanceddistally over the puller and into the gap. Following this step, thetractor is extended further outside of the catheter, and is in contactwith the walls of the vessel 211, through it does not have to be. Theouter diameter of the expanded tractor maybe narrower than the vesselinner diameter (ID) or it may be greater than then ID of the vessel (andmay therefore touch against them.

When advancing the catheter distally 222 (shown in arrows on left) andinto the gap, the puller may be held in position relative to thecatheter. In variations in which the tractor contacts the outer diameterof the vessel, this contact may hold the tractor in place against thevessel wall.

The steps of FIGS. 2B and 2C may be repeated multiple times to continueto advance the apparatus distally, however, in some variations it may bebeneficial to retract or reset the tractor back into the catheter, e.g.,by withdrawing the puller proximally to pull the tractor back into thecatheter. This is illustrated in FIG. 2D. In this example, the puller207 is withdrawn proximally 224 (arrows on left), so that the tractorcoupled to the puller 217 is pulled back into the catheter afterinverting over the distal end opening of the catheter. It may bebeneficial to perform this step after the catheter has been extendeddistally fully, e.g., until it pushes distally against the back of theinverting (bent-over) region, as shown in FIG. 2D. One the tractor hasbeen sufficiently retracted, the steps shown in FIGS. 2B-2C may berepeated, as shown in FIG. 2E, until the distal end opening of thecatheter is adjacent to the clot. After positioning next to the clot(and in some cases adjacent to it), vacuum may be applied to pull theclot into contact with the apparatus, and/or the device may be advancedby pushing the catheter distally while pulling the puller proximally toroll and invert the tractor into the catheter (see., e.g., FIG. 1H).

The method of advancing the apparatus described in FIGS. 2A-2E above maybe particularly helpful in advancing the apparatus within a vessel evenwithout the use of a guidewire or equivalent (e.g., guide catheter).However this method may also be used with a guidewire, as illustrated inFIGS. 3A-3D. In this example, the apparatus 300 is otherwise the same asshown in FIGS. 2A-2E, but may include or be used with a guidewire 355.In general, the same steps may be performed as discussed above.Alternatively, before or after a cycle of inching forward as describe inFIGS. 2A-2E, the apparatus may be slid distally along the guidewiretoward the clot. Thus, in some variations, this method may be used tohelp navigate the apparatus within congested or tortious regions whereadvancing by sliding may not be as effective.

Another method of advancing an apparatus distally using the tractor isillustrated in FIGS. 4A-4D. This method is also similar to that shown inFIGS. 2A-2E and 3A-3C above, but may extend the tractor portion evenfurther distally using the pusher, so that the pusher extends past thedistal end of the apparatus, out of the catheter. In contrast, in FIGS.2A-2E, the pusher remains substantially within the catheter, thussmaller ‘steps’ may be taken by the device.

In FIG. 4A, the apparatus is similar to that discussed above, includinga puller 407 that is connected at a distal end region 417 to a tractor403. The tractor is inverted over the distal end opening of a catheter405. The apparatus may be advanced within a vessel 411 towards a clot413, as shown in FIG. 4B, by advancing the inner puller 407 distally 420so that the puller distal end (and attached tractor) extends distallyfrom the catheter distal end opening. The tractor may tent, forming agap 419 or pouch between the distal end of the catheter and the distalface of the tractor (distal-facing end). In this example, the gap 419 isformed between the distal end of the catheter and the end of the puller.Thereafter, as shown in FIG. 4C, the catheter may be advanced distally422 within the gap of the tractor. In both this example and the exampleshown in FIGS. 2A-2E, the puller and tractor may be advanced distal ofthe catheter distally while the outer portion of the tractor remainsover the catheter, e.g. the second end of the tractor 414 that is shownextended over the outer diameter of the catheter remain proximal to thedistal end of the catheter. Once positioned near the clot 413, thetractor may be rolled into the catheter by pulling proximally on thepuller and (optionally) advancing the apparatus distally by pushing thecatheter distally.

If the distal end of the apparatus (e.g., the distal-facing, invertingtractor) is not adjacent to the clot 413, the steps above can berepeated, either with or without retracting the tractor into thecatheter (e.g., by pulling proximally on the puller). FIG. 4Dillustrates an example of retracting the tractor into the catheter bypulling proximally on the puller 424.

FIGS. 5A-5C illustrate the method of FIGS. 4A-4C with a guidewire 515.The apparatus may be the same (e.g., may include a puller 507 coupled ata distal end 517 to a flexible tractor 503 that is inverted over thedistal end opening of a catheter 505 and extending along the outersurface of the catheter). The steps may be the same as discussed above,including advancing the tractor and puller distally by pushing thepuller distally 520 towards a clot 513, as shown in FIG. 5B. Thecatheter may then be advanced (by sliding over the guidewire) as shownin FIG. 5C into the gap or pouch formed by the tractor 519. Oncepositioned near the clot 513, the tractor may be rolled into thecatheter by pulling proximally on the puller and (optionally) advancingthe apparatus distally by pushing the catheter distally.

FIGS. 6A-6B illustrate another method for advancing an apparatusdistally, in which both ends of the tractor 603 are coupled to axiallymovable elements. For example, in FIG. 6A the first end of the tractor603 is coupled to a puller 607 within the catheter 605. In addition, thesecond end of the tractor is shown coupled to an outer axially movablemember (second or outer catheter 619). This tri-axial system may be usedto inchworm the apparatus distally by alternately holding and pulling onthe various pullers and catheters. For example, in FIG. 6A, the tip ofthe apparatus may be advanced distally toward a clot by holding thecatheter fixed, allowing the puller to float (e.g., not constraining it)and pulling the outer catheter proximally 640. As a result, the outerportion of the flexible tractor may be pulled proximally, pulling thepuller and opposite end of the tractor distally, as shown in FIG. 6B.Thereafter, the puller may be held in place, the outer catheter may befree to move axially, and the catheter may be advanced distally into thegap formed by the tractor, which may drive the tractor distally (e.g.,back to the configuration shown in FIG. 6A) and pull the outer catheterdistally. These steps may be repeated as necessary. In some variationsthe outer catheter may be removably attached to the tractor, and thetractor may be pulled proximally to separate from the outer catheter.

A guidewire may also be used with this method. In this example, tipadvancement of the apparatus may take advantage of the outer (e.g.,guide) catheter stiffness (e.g., bending and column stiffness) to aid incatheter tip advancement. This may be particularly helpful inneurovascular regions, such as shown in FIG. 7.

FIG. 7 illustrate the uses of the methods described herein to advancethe apparatus 701 within a neurovascular structure such as the internalcarotid segment in the head. For example, the distal tip of theapparatus may be positioned at the distal tip of the internal carotidsegment; once positioned, an advancement method such as one of thosedescribed herein may be used drive the apparatus distally forwardtowards the clot. Such a method may create a pushing force forward fromthe internal carotid artery without sacrificing the trackability of theapparatus or the small outer diameter of the apparatus.

The apparatuses described herein may also be used to advance otherapparatuses (including catheters and tubes). For example, any of theseapparatuses and methods may be used in reverse (e.g. pulling proximallyon an outer portion of the catheter) to pull an apparatus within thelumen of the tractor distally for delivery at an internal vessel site.

Thus, to advance a tool (e.g., a tube, etc.) into the patient, a tractorinserted into the body (which may be advanced as descried herein, evenfor use without performing a thrombectomy or in addition to athrombectomy) may be pulled from the outside of the catheter proximally(e.g., with an overtube or pull wire) to invert the tractor in theopposite direction from out of the catheter. As the tractor on the OD ofthe catheter is pulled proximally, it may advance a tool (e.g., tube)inside the apparatus to the target location in the patient. Thismechanism could be used in a variety of applications including; passingmature clot or vessel lesion, placing an intubation system (e.g., in athroat), providing rectal or vaginal access, performing NOTES surgery,inserting a tool such as a trocar, inserting a scope into a body region(e.g., gastrointestinal region, colon, blood vessel lumen, etc.),inserting a robotic tool, crossing a calcified vessel, etc. Otherapplications of the apparatuses and methods of removing and/or placingmaterial using the apparatuses described herein may include includeremoval of tissue, such as gall bladder removal and removal of fat(liposuction). For example a cutting or ablative tool may be passed downthe middle of the apparatus, through the catheter, the puller and thetractor, and extended from the distal end, where it may be used to cuttissue that may then be pulled out of the body using the tractor bypulling the tractor proximally within the catheter. Note that thismethod may be used to remove both the tool and/or the cut tissue. Thus,despite referring to these apparatuses as mechanical mechanicalthrombectomy apparatuses herein, any of these devices may be adapted foruses not limited to thrombectomy, and may alternatively be referred toas mechanical tractor apparatuses.

Also described herein are powered mechanical thrombectomy apparatuses inwhich the tractor may be driven by a driver such as an electrical motor.For example, FIG. 8A illustrates an example of a power driven tractor ina mechanical thrombectomy apparatus. The apparatus may drive the tractorcontinuously in a loop, thus the tractor may be configured as a closedloop, belt or toroid of material that extends around a catheter. Thepower drive may run the apparatus in either the forward or reversedirections. In FIG. 8A, the tractor comprises a plurality of belts 803that extend around and through the catheter 805. A drive motor 811drives rotation of the belts. In FIG. 8A the drive motor drives a ring813 that can therefor drive multiple belts forming the tractor or insome variations, a single torus that passes over the supportingcatheter. The catheter may include holes or openings 817 into which thebelts forming the tractor may reside. The belts extend along the lengthof the catheter 805. In this example, a hub 815 holds the proximal endof the catheter and holds the belts against the drive motor and/or drivering that is driven by the drive motor, and may also connect to a vacuum819.

FIG. 8B shows an enlarged view of a catheter and tractor that may beused with the apparatus shown in FIG. 8A. FIG. 8B shows the catheter 805including a plurality of belts 803, 803′ forming the tractor. The beltspass through an opening in the catheter at the proximal end, but rollover the distal end of the catheter, and extend along the outer andinner longitudinal axis.

FIGS. 9A-9B illustrates an example of operation of a power drivenmechanical thrombectomy apparatus configured to grab a clot. In FIG. 9A,the apparatus 900 is similar to that shown in FIG. 8A, above, includinga plurality of belts 903, 903′ forming the tractor, and an internalcatheter 905; the bests rotate down the length of the catheter. Notethat the catheter may be rigid or flexible. The catheter may includechannels, and/or notches or other guide along its length for guidingand/or enclosing the belts at various portions. In FIG. 9A, theapparatus is positioned adjacent to a clot 924. The clot may initiallybe grabbed using aspiration (e.g., vacuum). In FIG. 9B, the apparatusmay is shown after grabbing the clot, and compressing it within thecatheter.

Note that the power-driven mechanical thrombectomy apparatuses shown inFIGS. 9A and 9B do not include a puller, as the motor may act like apuller. In some variations a separate puller may be used.

As mentioned above, any of the apparatuses described herein may be usedwith an additional outer catheter, including the powered apparatusesdescribed herein. For example, FIG. 9C illustrates an example of apowered apparatus 900 used with an intermediate catheter having a largerOD than the powered mechanical thrombectomy apparatus. In this example,the length of the apparatus is slightly greater or almost equal to thelength of the intermediate catheter 930, so that just the distal endregion of the apparatus, including the inverting tractor (belts) isaccessible and/or sticks out 933 of the intermediate catheter.Alternatively, the apparatus may be retracted into the outer(intermediate) catheter slightly, or may extend substantially from theend of the outer catheter.

Any of the methods (including user interfaces) described herein may beimplemented as software, hardware or firmware, and may be described as anon-transitory computer-readable storage medium storing a set ofinstructions capable of being executed by a processor (e.g., computer,tablet, smartphone, etc.), that when executed by the processor causesthe processor to control perform any of the steps, including but notlimited to: displaying, communicating with the user, analyzing,modifying parameters (including timing, frequency, intensity, etc.),determining, alerting, or the like.

When a feature or element is herein referred to as being “on” anotherfeature or element, it can be directly on the other feature or elementor intervening features and/or elements may also be present. Incontrast, when a feature or element is referred to as being “directlyon” another feature or element, there are no intervening features orelements present. It will also be understood that, when a feature orelement is referred to as being “connected”, “attached” or “coupled” toanother feature or element, it can be directly connected, attached orcoupled to the other feature or element or intervening features orelements may be present. In contrast, when a feature or element isreferred to as being “directly connected”, “directly attached” or“directly coupled” to another feature or element, there are nointervening features or elements present. Although described or shownwith respect to one embodiment, the features and elements so describedor shown can apply to other embodiments. It will also be appreciated bythose of skill in the art that references to a structure or feature thatis disposed “adjacent” another feature may have portions that overlap orunderlie the adjacent feature.

Terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.For example, as used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, steps, operations, elements, components, and/orgroups thereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items and may beabbreviated as “/”.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of over and under. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Although the terms “first” and “second” may be used herein to describevarious features/elements (including steps), these features/elementsshould not be limited by these terms, unless the context indicatesotherwise. These terms may be used to distinguish one feature/elementfrom another feature/element. Thus, a first feature/element discussedbelow could be termed a second feature/element, and similarly, a secondfeature/element discussed below could be termed a first feature/elementwithout departing from the teachings of the present invention.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising” means various components can be co-jointlyemployed in the methods and articles (e.g., compositions and apparatusesincluding device and methods). For example, the term “comprising” willbe understood to imply the inclusion of any stated elements or steps butnot the exclusion of any other elements or steps.

In general, any of the apparatuses and methods described herein shouldbe understood to be inclusive, but all or a sub-set of the componentsand/or steps may alternatively be exclusive, and may be expressed as“consisting of” or alternatively “consisting essentially of” the variouscomponents, steps, sub-components or sub-steps.

As used herein in the specification and claims, including as used in theexamples and unless otherwise expressly specified, all numbers may beread as if prefaced by the word “about” or “approximately,” even if theterm does not expressly appear. The phrase “about” or “approximately”may be used when describing magnitude and/or position to indicate thatthe value and/or position described is within a reasonable expectedrange of values and/or positions. For example, a numeric value may havea value that is +/−0.1% of the stated value (or range of values), +/−1%of the stated value (or range of values), +/−2% of the stated value (orrange of values), +/−5% of the stated value (or range of values), +/−10%of the stated value (or range of values), etc. Any numerical valuesgiven herein should also be understood to include about or approximatelythat value, unless the context indicates otherwise. For example, if thevalue “10” is disclosed, then “about 10” is also disclosed. Anynumerical range recited herein is intended to include all sub-rangessubsumed therein. It is also understood that when a value is disclosedthat “less than or equal to” the value, “greater than or equal to thevalue” and possible ranges between values are also disclosed, asappropriately understood by the skilled artisan. For example, if thevalue “X” is disclosed the “less than or equal to X” as well as “greaterthan or equal to X” (e.g., where X is a numerical value) is alsodisclosed. It is also understood that the throughout the application,data is provided in a number of different formats, and that this data,represents endpoints and starting points, and ranges for any combinationof the data points. For example, if a particular data point “10” and aparticular data point “15” are disclosed, it is understood that greaterthan, greater than or equal to, less than, less than or equal to, andequal to 10 and 15 are considered disclosed as well as between 10 and15. It is also understood that each unit between two particular unitsare also disclosed. For example, if 10 and 15 are disclosed, then 11,12, 13, and 14 are also disclosed.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

The examples and illustrations included herein show, by way ofillustration and not of limitation, specific embodiments in which thesubject matter may be practiced. As mentioned, other embodiments may beutilized and derived there from, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. Such embodiments of the inventive subject matter maybe referred to herein individually or collectively by the term“invention” merely for convenience and without intending to voluntarilylimit the scope of this application to any single invention or inventiveconcept, if more than one is, in fact, disclosed. Thus, althoughspecific embodiments have been illustrated and described herein, anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

What is claimed is:
 1. A method of removing a clot from a vessel using amechanical thrombectomy apparatus including a catheter extending from aproximal end to a distal end, a puller extending distally within thecatheter and a flexible and tubular tractor, wherein the tractor iscoupled to a distal end region of the puller and further wherein thetractor is inverted over a distal end opening of the catheter so thatthe tractor extends proximally over the catheter, the method comprising:advancing the puller distally within the catheter and within the vesseltowards a clot, so that the tractor extends from the puller distallybeyond the distal end opening of the catheter, forming a gap between thetractor and the distal end opening of the catheter; advancing thecatheter distally over the puller and into the gap; repeating theadvance steps until the distal end opening of the catheter is adjacentto the clot; and drawing the clot into the catheter with the tractor bypulling the tractor proximally within the catheter so that the tractorrolls and inverts over the distal end opening of the catheter.
 2. Themethod of claim 1, wherein repeating further comprises comprisingpulling the pusher proximally within the catheter to invert a portion ofthe tractor over the distal end opening of the catheter.
 3. The methodof claim 1, wherein drawing the clot into the catheter further comprisesadvancing the catheter distally while pulling the pusher proximally. 4.The method of claim 1, wherein advancing the puller distally comprisesadvancing the puller without using a guidewire extending distal to thepuller.
 5. The method of claim 1, wherein advancing the puller comprisesextending the distal end of the puller out of the distal end opening ofthe catheter.
 6. The method of claim 1, wherein advancing the pullercomprises extending the tractor distally within the vessel, furtherwherein the tractor comprises a woven flexible and tubular tractor. 7.The method of claim 1, wherein advancing the puller comprises extendingthe tractor distally within the vessel, further wherein the tractorcomprises a knitted tractor.
 8. The method of claim 1, wherein advancingthe puller comprises extending the tractor distally within the vessel,further wherein the puller comprises a central lumen configured to passa guidewire therethrough.
 9. The method of claim 1, wherein advancingthe puller comprises advancing the puller within an internal carotidartery.
 10. A method of removing a clot from a vessel using a mechanicalthrombectomy apparatus having a puller within a first catheter that iswithin a second catheter, wherein the puller and second catheter areconnected by a flexible and tubular tractor, the method comprising:advancing the puller distally through the first catheter and the secondcatheter and within the vessel towards a clot, so that the flexible andtubular tractor extends from the puller beyond a distal end opening ofthe first catheter and beyond a distal end opening of the secondcatheter; advancing the outer catheter distally through the vessel byone or more of: holding the position of the first catheter within thevessel and pulling the puller proximally within the first catheter; ormoving the first catheter distally relative to the puller; and drawingthe clot into the first catheter with the flexible and tubular tractorby pulling the flexible and tubular tractor proximally within the firstcatheter so that the flexible and tubular tractor rolls and inverts overthe distal end opening of the catheter.
 11. The method of claim 10,further comprising repeating the advancing steps until the clot isadjacent to the distal end of the puller.
 12. The method of claim 10,wherein drawing the clot into the catheter further comprises advancingthe first catheter distally while pulling the pusher proximally.
 13. Themethod of claim 10, wherein advancing the puller distally comprisesadvancing the puller without using a guidewire extending distal to thepuller.
 14. The method of claim 10, wherein advancing the pullercomprises extending the flexible and tubular tractor distally within thevessel further wherein the flexible and tubular tractor comprises awoven flexible and tubular tractor.
 15. The method of claim 10, whereinadvancing the puller comprises extending the flexible and tubulartractor distally within the vessel further wherein the flexible andtubular tractor comprises a knitted flexible and tubular tractor. 16.The method of claim 10, wherein advancing the puller comprises extendingthe flexible and tubular tractor distally within the vessel furtherwherein the puller has a central lumen configured to pass a guidewiretherethrough.
 17. The method of claim 10, wherein advancing the pullercomprises advancing the puller within an internal carotid artery. 18.The method of claim 10, wherein drawing the clot into the first cathetercomprises uncoupling the flexible and tubular tractor from the secondcatheter.
 19. A mechanical thrombectomy apparatus for removing a clotfrom a vessel, the apparatus comprising: a flexible catheter having adistal end and a distal end opening; a tractor comprising a flexiblebelt that extends within the catheter, inverts over the distal endopening of the catheter and extends along the outer diameter of thecatheter; a power drive at a proximal end of the flexible catheterconfigured to drive the tractor around the catheter so that it invertsover the distal end opening of the catheter; and a guidewire lumenthrough the catheter and the tractor configured to pass a guidewire. 20.The apparatus of claim 19, wherein the flexible belt comprises aflexible tube.
 21. The apparatus of claim 19, wherein the tractorcomprises a plurality of flexible belts that each extend within thecatheter, invert over the distal end opening of the catheter and extendalong the outer diameter of the catheter.
 22. The apparatus of claim 19,wherein the power drive is configured to engage with the flexible belton an outer surface of the catheter.
 23. The apparatus of claim 19,wherein the power drive comprises an annular ring surrounding thecatheter and the tractor.
 24. The apparatus of claim 19, furthercomprising an outer catheter configured to enclose the flexible catheterand tractor, wherein the flexible catheter and tractor may be insertedthrough the body within the outer catheter.